.nav {
    width: 100%;
    height: 77px;
    background-color: rgba(0,0,0,.5);
}
.nav .logo {
    float: left;
    width: 127px;
    height: 44px;
    margin-top: 16px;
}
.nav .logo img {
    display: block;
    width: 100%;
    height: 100%;
}
.nav  .nav-box {
    float: right;
    margin-top: 29px;
}
.nav-box .nav-item {
    float: left;
    margin-right: 36px;
    font-size: 16px;
    line-height: 17px;
    color: #ffffff;
    text-align: center;
}
.nav-box .nav-item a {
    color: #ffffff;
}
.nav-box .nav-item div {
    width: 41px;
    height: 2px;
    background-color: red;
    margin: 0 auto;
    margin-top: 13px;
    opacity: 0;
}
.nav-box .selected a {
    color: red;
}
.nav-box .selected div {
    opacity: 1;
}
.nav-box .nav-item:hover a {
    color: red;
}
.nav-box .nav-item:hover div {
    opacity: 1;
}